<!DOCTYPE html>
<html lang="en">

<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Document</title>
  <link rel="stylesheet" href="./index.css">
  <style>
    div {
      color: red;
    }
  </style>
</head>

<body>
  <div style='background-color: black;'>
    云课堂
  </div>
</body>

</html>